Epidural catheter misplaced into the thoracic cavity: Utilized to provide interpleural analgesia.

Thoracic epidural analgesia is one of the most effective and time-tested modalities of providing postthoracotomy pain relief. It improves postoperative pulmonary outcome. Nevertheless, being a blind procedure several complications have been associated with the technique. Pleural puncture is one rare complication that might occur following thoracic epidural catheterization. We have discussed a patient who underwent a right thoracotomy for excision of emphysematous bulla of lung under general anesthesia with thoracic epidural. The epidural catheter was misplaced in the pleural cavity and was detected intraoperatively after thoracotomy. The catheter was left in situ and was successfully utilized to provide postoperative analgesia via the interpleural route.

INTRODUCTION

Thoracic epidural analgesia is an efficient and time-tested method of providing intraoperative and postoperative pain relief for a wide range of surgical procedures including thoracotomy, thoracoscopy, sternotomy, upper abdominal surgeries. However, due to the blind nature of the procedure, it has been associated with several complications like dural perforation, postdural puncture headache, subdural placement of catheter, direct needle trauma to the nerve routes leading to radiculopathy, epidural hematoma, intravascular injection, venous air embolism, epidural abscess, total spinal/subdural anesthesia, breakage of catheter, backache, etc. Interpleural misplacement of a thoracic epidural catheter is one rare technique-related complication. We have discussed a case in which the epidural catheter was detected during the surgery to be misplaced into the thoracic cavity. The catheter was retained in situ and was successfully utilized to provide interpleural analgesia.

CASE REPORT

A 54-year-old male patient, weight 70 kg and height 168 cm and body mass index 24.82 presented with chronic intermittent cough and breathlessness on exertion and diagnosed to have an emphysematous bulla in the upper lobe of right lung based on his chest radiograph and computed tomography chest findings. He had no co-morbidities, his effort tolerance was 4–6 metabolic equivalents, and his blood investigations were within normal limits. General examination and cardiovascular system were normal. Airway examination did not reveal any difficulty and his spine was normal.

He was scheduled for an elective right upper lobe bulla excision via right posterolateral thoracotomy. In the operating room, monitors were connected, and baseline parameters were recorded. Patient was hydrated with 500 ml of ringers lactate, premedicated with injection glycopyrrolate and injection midazolam. Epidural catheterization was performed in the left lateral position with 18-gauge Tuohy's needle in the T7-T8 interspace through the median approach. We could not identify the epidural space after three attempts; hence the paramedian approach was tried and epidural space was identified using loss of resistance to air and saline. Epidural catheter was inserted freely without any resistance; directed cephalad and fixed at 9 cm from skin level. There was no respiratory distress or cough during or immediately after the procedure. Test dose was given with injection lignocaine 1.5% 3 ml with 1 in 200,000 adrenaline to rule out intrathecal or intravascular placement.

Patient was induced as per the institute protocol with fentanyl, thiopentone, vecuronium, and intubated with 35 French left-sided double lumen endotracheal tube. Tube position was confirmed by auscultation. Patient was positioned in left lateral. Anesthesia was maintained with oxygen, nitrous oxide, and sevoflurane 2%. Prior to skin incision, bupivacaine 0.25% 10 ml was injected via epidural catheter after negative aspiration of blood/cerebrospinal fluid. Surgeon proceeded with thoracotomy. Intraoperatively patient was maintained in one lung ventilation; his vitals were stable, and there were no clinical signs indicating insufficient analgesia. Epidural top up was repeated after 1 h with 8 ml of 0.25% bupivacaine. After excision of bullae, the surgeon noticed the tip of the epidural catheter to be in the right pleural cavity. The catheter was visible up to the 5 cm marking, as shown in Figure 1. There was no evidence of active bleeding or injury to the lung tissue around the catheter site. Hence, we decided to leave the catheter in place and utilized it to provide interpleural analgesia in the postoperative period. We had ruled out contraindications of interpleural analgesia prior to injection of local anesthetic. During the closure of the thoracic cage, 20 ml of 0.25% bupivacaine with morphine 3 mg was injected through the epidural catheter and the intercostal drain (I.C.D.) was clamped for 30 min. Diclofenac 75 mg intravenous (i.v.) was given to attenuate visceral pain. The patient was reversed and extubated. Patient was comfortable and did not complain of pain after emergence from general anesthesia.

Figure 1

Epidural catheter lying in the thoracic cavity

Postoperative monitoring and pain assessment were done in the intensive care unit. A visual analog score (VAS) on a scale of 0–10, with 0 indicating no pain and 10 indicating worst possible pain, was used for pain assessment. 4 h after emergence from anesthesia, patient complained of pain in the incision site. A bolus of 20 ml of 0.5% bupivacaine was given, and I.C.D. was clamped for 30 min. VAS improved from 7 to 4. Thereafter, top up was given every 6 h with 20 ml 0.25% bupivacaine; each time clamping the I.C.D. for about 30 min after injection of the drug. Injection tramadol 50 mg i.v. 8th hourly and injection diclofenac 75 mg i.v. 12th hourly were added. Pain scores and vitals were monitored every 2 h for 24 h. Patient was closely monitored for signs of local anesthetic toxicity as well. Postoperative analgesia in the patient was effective; with VAS between 2 and 4 and no additional analgesic was required. Vitals were stable, except for once when he developed hypotension with systolic blood pressure of 80 mmHg which responded to i.v. fluids and ephedrine administration. The catheter was removed intact after 24 h.

DISCUSSION

The incidence of pleural puncture following thoracic epidural is difficult to determine; though quite a few such cases have been mentioned in the literature.[1234] The outcome of such a complication is variable. It may go unnoticed and uneventful or may lead to serious complications such as hemothorax[5] or pneumothorax.[6]

For mid-thoracic epidural catheterization, the paramedian approach is now favored by most anesthesiologists. Literature reviews support the fact that the incidence of pleural puncture is higher with the paramedian approach than the median approach. The proposed reasons for the higher incidence of misplacement with this approach are inability to identify skin landmarks, inappropriate angle of insertion of the Tuohy needle during paramedian approach, very thin individuals, etc.[23] However, pleural puncture with the median approach has also been reported.[78]

In our patient, we could recognize this complication because the catheter tip was located in the ipsilateral pleural cavity. A catheter which has migrated into the contralateral pleural cavity would go unnoticed.

Inoue et al.[1] described three cases of pleural puncture during thoracic epidural. Catheter was retained in all three cases to provide interpleural analgesia. Interpleural route has been satisfactorily used to provide analgesia after thoracotomy.[910] It is a better modality when compared to other routes of pain relief like parenteral opioids, intercostal block, etc. The analgesic effect of local anesthetic in interpleural route is due to its diffusion through the parietal pleura and intercostalis minimus muscle causing a blockade of paravertebral nerves. Opioids can be added as adjuvants to local anesthetics as opioid receptors have been identified in the peripheral nervous system.

Both the loss of resistance technique and hanging drop technique are not reliable to clearly distinguish epidural space from the pleural cavity. Hence, the following recommendations are suggested for a successful epidural catheterization:

(1) Ensure that the patient positioning is optimal for the procedure. (2) In selected cases, determination of depth of the epidural space from the skin can be done preoperatively using ultrasound guidance. (3) Avoid multiple punctures in the same space to prevent the formation of a subcutaneous false track. (4) If a resistance is encountered during catheter insertion, it should be withdrawn. The catheter should never be inserted forcefully. (5) It is advantageous if catheter is inserted before induction of general anesthesia; when the patient is awake. It gives us the opportunity to inject local anesthetic and assess neural blockade. Presence of bilateral sensory blockade would confirm epidural placement. If the blockade is unilateral then interpleural placement could be a possibility.

CONCLUSION

We conclude by stating that while performing a thoracic epidural anesthesia, it is important to keep in mind such rare technique-related complications. If unintentional pleural puncture after epidural catheterization is detected in a patient during surgery, administration of local anesthetic through the intrapleural route could be considered as a potential alternative to provide postoperative analgesia after thoracotomy or thoracoscopy procedures; under stringent monitoring conditions.